Swanson has been out since Sept. 25 with a partially torn ligament in his hand, and the issue is bad enough to keep him off the playoff roster for the opening series.
The 24-year-old finished the season hitting .238 with 14 home runs and 10 stolen basis in 136 games.
Perhaps most importantly, he is an above-average defender at a premium position who ranked third in the National League with a .981 fielding percentage at shortstop, per Baseball Reference.
The Braves were reportedly "cautiously optimistic" that Swanson would be healthy enough to return to the field in time for the start of the postseason, per Gabe Burns of the Atlanta Journal-Constitution. Unfortunately, he felt discomfort after taking swings on Saturday, according to Mark Bowman of MLB.com.
Swanson will hope he can be healthy enough to play in time for the NLCS, assuming Atlanta is able to advance beyond the first round.
Meanwhile, utilityman Charlie Culberson will likely move into the starting lineup at shortstop after filling in for Swanson over the final week of the regular season.
The 29-year-old has played seven different positions this season—everything but catcher and center field—including 15 starts at shortstop. After hitting .270 with a .792 OPS this year, the Braves will be in good shape even without one of their top young players.